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Snaped a chinese cutter. My fault?

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  • Snaped a chinese cutter. My fault?

    Hi, I recently tryed puting some notchs in some 1/8" thick hot rolled (1018?) using a 1/4" 2 flute ball nose endmill at 300rpm (slow I know..)

    It worked fine as long as I took passes about 0.1" deep, but I tryed one slot at 0.5" deep and it basicly snaped before getting half way in. The entire time it was cutting (even the shallow passes) it made a 'snaping' noise. I only fed at about 4 to 6IPM, Snaped about half way up the flutes. (1 1/2" flute length or so..)

    Was this my fault for feeding too deep? Too fast feed for the RPM? (Aka too high of chip load per tooth) Or just a bad chinese cutter improperly ground/heat treated or somesuch?

    When I finished the job with my 5/16 (that turns out the 1/4" was too narrow anyway!), it did'nt make that 'snaping' noise while cutting normaly at same RPM and same 0.1" DOC, Did not try doing any more one pass 0.5" DOC's. made a much better cutting noise like my standard endmills.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

  • #2
    BlacMoons,
    As you mentioned, way too slow and too fast a feed, and .5 DOC is pretty much out of the question.

    Live and lean, who hasn't done the same.

    I am not even going to mention further on the Chinese EM, you'll discover the truth fast enough.

    Comment


    • #3
      I suppose you should have backed off on depth of cut,or feed rate if you heard a snapping noise. That might have been the result of the cutter actually flexing some,and snapping back straight just as it finished each cut.

      Regardless, I generally have found that Asian HSS is on the more brittle side . Another problem with them seems to be inconsistent sharpness. Some will be quite sharp,while others just do not have that keen edge.

      Maybe you should check the edge before using an end mill,and hone it a bit if necessary.

      Comment


      • #4
        If you need a radius at the bottom of the slot, cut it with a regular end mill and then put the ball nose in.

        That should eliminate the snapping noise.

        Also, 1/2 inch DOC is pretty deep with a 1/4 inch end mill in steel.

        And way too slow, try around 7-800.

        Coolant?

        Brian
        OPEN EYES, OPEN EARS, OPEN MIND

        THINK HARDER

        BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

        MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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        • #5
          A ball nose end mill cannot be fed anywhere near as fast as a regular end mill. The problem is that the cutting edges have a variable SFM which approaches zero as the edge nears the tip of the ball. Any attempt to use it like a regular end mill is inviting trouble as you found out.
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            Originally posted by Black_Moons
            Hi, I recently tryed puting some notchs in some 1/8" thick hot rolled (1018?) using a 1/4" 2 flute ball nose endmill at 300rpm (slow I know..)

            It worked fine as long as I took passes about 0.1" deep, but I tryed one slot at 0.5" deep and it basicly snaped before getting half way in. The entire time it was cutting (even the shallow passes) it made a 'snaping' noise. I only fed at about 4 to 6IPM, Snaped about half way up the flutes. (1 1/2" flute length or so..)

            Does NOBODY ELSE see a BIG PROBLEM with the above?

            He has 1/8" thick 1018.... HOW DID HE GET 0.5" DEEP CUTS?

            He had to be going in and cutting through the thickness of the material from the 'face" of it. Dunno about you folks, but no way would I do that..... I would cut in from the 1/8" face if the notches were on the edge, as it seems they must be.

            The snapping noise he mentions is probably the material as the tooth leaves it and the thin material snaps back as the cutting force is released....

            Me, I would have bagged the ball end cutter and depended on the radius of the cutter to create the rounded bottom of the notch, if I "see" this correctly. Coming in from teh edge of the material it should work great.

            The 1/8" thick material should cut like butter.

            As for 1/2" deep, I have done that with a 3/8" roughing cutter, in 1018, and was able to feed about as fast as I could crank the mill..... and I only have 1/4 HP. The cutter was chinese , too. I was cutting the adjustment slot in a replacement steady rest jaw.
            Last edited by J Tiers; 10-23-2010, 11:35 PM.
            1601

            Keep eye on ball.
            Hashim Khan

            Comment


            • #7
              Ha-Ha, good call JT, I did not see that

              There was just too much wrong for that operation to have a good outcome.

              Comment


              • #8
                Originally posted by Ken_Shea
                Ha-Ha, good call JT, I did not see that
                Not only did you break a cutter but you broke the laws of TIME AND SPACE!
                This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
                Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numb
                Plastic Operators Dot Com

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                • #9
                  Hah, In retro spect it was more like 0.3" DOC, but the 1/8" thick peice was mounted verticaly in the vise, ie I was trying to put a rounded nose in it, Like you would if you side milled a sheet of steel with a normal endmill, but I wanted to facemill it because well, It was harder to mount that thing on its side and not crush the internal threads..

                  I was making one of these: http://motorbicycling.com/attachment...ng-screwin.jpg
                  Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

                  Comment


                  • #10
                    Sounds like your workpiece was flexing while being mounted in the vise. This will break endmills as well.

                    Comment


                    • #11
                      Originally posted by Liger Zero
                      Not only did you break a cutter but you broke the laws of TIME AND SPACE!
                      Wasn't me that broke that cutter, but I've done my share over the years, almost always due to lack of attention, unnecessary expense is a great teacher.

                      Comment


                      • #12
                        Why guess? Every manufacturer (except the Chinese) has extensive material of cutting recommendations. Surface speed, DOC, feed per tooth, lubrication. Consult it, consume less mills.

                        A ball nose cutter cuts much better when you tilt it (or the work) so that the center line of the cutter is not in contact with the material.
                        Say you tilt the mill's head by 30° and and feed such way the tip of the cutter points away from the feeding direction (drag, like with a pen), you no longer have the zero-speed-problem on the tip.


                        Nick

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                        • #13
                          300 rpm is a bit slow and if the feed was to fast then yup you broke,it , in steel i always mill at 400 to 450 max and slow feed and even i can take 30 thou or more and not think twice about it with chiness cutters, 300 rpm you would have to take extreamly slow on the feed,even at 30 thou or more might fall alsleep to ,

                          but its all cool, took me a bit to learn my mill and its limints and a few broken cutters alonge the way and i snaped a few really costly ones man it hurt but it happens,

                          Comment


                          • #14
                            I think you are still off. You must mean 0.03" or 0.003" but not 0.300" since 1/8" = 0.125".


                            Originally posted by Black_Moons
                            Hah, In retro spect it was more like 0.3" DOC, but the 1/8" thick peice was mounted verticaly in the vise, ie I was trying to put a rounded nose in it, Like you would if you side milled a sheet of steel with a normal endmill, but I wanted to facemill it because well, It was harder to mount that thing on its side and not crush the internal threads..

                            I was making one of these: http://motorbicycling.com/attachment...ng-screwin.jpg
                            "Work hard. Tell everyone everything you know. Close a deal with a handshake. Have fun!"

                            -- Harold "Doc" Edgerton

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                            • #15
                              One other thing that I don't see mentioned.

                              1 1/2 inch flute length on a 1/4 inch end mill is way longer than standard length.

                              I wouldn't use an extra long end mill unless I had a need to reach extra deep into a slot.

                              Brian
                              OPEN EYES, OPEN EARS, OPEN MIND

                              THINK HARDER

                              BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                              MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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